"The Sun takes 225 million Earth years to make one rotation. This period of time is called a cosmic year."

225 million years

The sun is one of hundreds of billion of stars in our galaxy, the Milky Way.
The galaxy is composed of gaseous interstellar medium, neutral or ionized, sometimes
concentrated into dense gas clouds made up of atoms molecules, and dust. All of
the matter -- gas, dust, and stars -- rotate around a central axis perpendicular
to the galactic plane. The centrifugal force caused by the rotation balances out
the gravitational force, which draw all the matter toward the center.

The mass is located within the circle of the Sun's orbit through the galaxy
is about 100 billion times the mass of the Sun. Because the Sun is about average
in mass, astronomers have concluded that the galaxy contains about 100 billion
stars within its disk.

All stars in the galaxy rotate around a galactic center but not with the same
period. Stars at the center have a shorter period than those farther out. The
Sun is located in the outer part of the galaxy. The speed of the solar system
due to the galactic rotation is about 220 km/s. The disk of stars in the Milky
Way is about 100,000 light years across and the sun is located about 30,000 light
years from the galaxy's center. Based on a distance of 30,000 light years and a
speed of 220 km/s, the Sun's orbit around the center of the Milky Way once every
225 million years. The period of time is called a cosmic year. The Sun has orbited
the galaxy, more than 20 times during its 5 billion year lifetime. The motions
of the period are studied by measuring the positions of lines in the galaxy spectra.